This invention relates to method and apparatus for resecting a bone. In particular this invention relates to a method and apparatus for performing all of the bone resections required for implanting a prosthesis using one bone resection instrument such as a cutting block. More particularly, this invention relates to a navigated cutting block that can be “floated” around the bone to be resected to set up the planes for resection.
There are several types of prostheses known in the art. One type is sometimes referred to as a “resurfacing type”. In these prostheses, the articular surfaces of the bones are “resurfaced” with articular bearing components. One important aspect of these procedures is the correct resection of the bones. These resections must provide planes which are correctly angled in order to properly accept the prosthetic components.
Recently, various computerized navigation systems have been introduced to aid the practitioner during different surgical procedures. These systems include multiple video cameras which are deployed above the surgical site and a plurality of dynamic reference frame (DRF) devices, also known as trackers, which are attached to body parts and surgical instruments. The trackers can be LED devices or reflective spheres which are visible to the cameras. These trackers are attached to body parts and the surgical instruments and preferably include light emitting devices, such as light emitting diodes which are visible to the video cameras. The trackers communicate position information to a camera system located in the operating room. The camera system is connected to a computer which tracks the location of the tracker and the patient and displays the relationship on a CRT. Using software designed for a particular surgical procedure, a computer receiving input from the cameras guides the placement of surgical instruments such as cutting blocks for bone resection.
The prior art cutting blocks have several shortcomings. In case of a total knee arthroplasty that involves the replacement of portions of the patella, femur and tibia with artificial components, separate distal resection block and a block for making remaining resections on the femur are required. Also, different size resection blocks are required for different size implants. This increases the inventory of parts in the operating room. Additionally the prior art cutting blocks are sized in proportion to the size of the implant and are not very suitable for minimally invasive surgery. Therefore, there is a need for a navigable cutting block that is small in size, suitable for use with all sizes of implants and allows for all the necessary resections using a single cutting block.
As used herein, when referring to bones or other parts of the body, the term “proximal” means closer to the heart and the term “distal” means more distant from the heart. The term “inferior” means toward the feet and the term “superior” means towards the head. The term “anterior” means towards the front part of the body or the face and the term “posterior” means towards the back of the body. The term “medial” means toward the midline of the body and the term “lateral” means away from the midline of the body.